Current technologies attempt to create the visual perception of a free-floating image through the manipulation of depth cues generated from two-dimensional data employing well-established techniques. A few examples of these include stereoscopic imaging via shutter or polarized glasses, as well as auto-stereoscopic technologies composed of lenticular screens directing light from a conventional display, or real-imaging devices utilizing concave mirror arrangements. All of these technologies suffer convergence and accommodation limitations. This is a function of the original two-dimensional image generating data and its disparity to its perceived spatial location, resulting in user eyestrain and fatigue due to the difficulty of focusing on an image that does not truly exist where it is perceived to occur.
In order to resolve this visual limitation, the image and its perceived location must coincide spatially. A well-established method solving this constraint is by projection onto an invisible surface that inherently possesses a true spatially perceived image location; yet prior art methods rendered poor image fidelity. Projection onto non-solid screens was first suggested in 1899 by Just, in U.S. Pat. No. 620,592, where an image was projected onto a simple water screen known in the art as fog screen projections. Since then, general advancements to image quality have been described depending solely on improving the laminar quality of the screen directly correlating to image quality. As such in prior art, these methodologies limit the crispness, clarity, and spatial image stability solely based on the dynamic properties of the screen, which intrinsically produce a relatively spatially unstable image. Minor screen fluctuations further compound images distortion. Image fidelity was further compromised and image aberrations amplified by the easily discernible screen detracting from the intended objective of free-space imaging. Advancements in this invention allow the device to be self-sustainable, and overcome prior art limitations of image stability and fidelity, improve viewing angles, and incorporate additional interactive capabilities.
One of the main disadvantages found in prior art was the reliance on a supply of screen generating material. These devices depended on either a refillable storage tank for the screen generating material, or the device had to be positioned in or around a large body of water such as a lake in order to operate. This limited the operating time of the device in a closed environment such as in a room required refilling, or a plumbing connection for constant operation. The result severely limited the ease of operation, portability, and placement of the device caused by this dependence. Furthermore, some fog screen projection systems changed the operating environment by over-saturating the surrounding ambient air with particulates, such as humidity or other ejected gases. The constant stream of ejected material created a dangerous environment, capable of short-circuiting electronics as well as producing a potential health hazard of mold build-up in a closed space, such as in a room. The dehumidification process disclosed both in Kataoka's U.S. Pat. No. 5,270,752 and Ismo Rakkolainen's WAVE white paper, was not employed to collect moisture for generating the projection surface screen but rather to increase laminar performance as a separate detached aspirator. The present invention employs condensate extraction method specifically to serve as a self-sustained particle cloud manufacturing and delivery system.
Furthermore in prior art, while the projection surface can be optimized for uniformity, thickness, and planarity by improving laminar performance, the inherent nature of a dynamic system's natural tendency towards turbulence will ultimately affect the overall imaging clarity or crispness and image spatial stability such as image fluttering. These slight changes caused by common fluctuating air currents and other environmental conditions found in most indoor and outdoor environments induce an unstable screen, thereby affecting the image. Prior art attempted to solve these image degradation and stability issues by relying on screen refinements to prevent the transition of laminar to turbulent flow. Kataoka's, U.S. Pat. No. 5,270,752 included improvements to minimize boundary layer friction between the screen and surrounding air by implementing protective air curtains, thereby increasing the ejected distance of the screen size while maintaining a relatively homogeneous laminar thin screen depth and uniform particulate density for a stable image. While a relatively laminar screen can be achieved using existing methodologies, generating a spatially stable and clear image is limited by depending solely on improvements to the screen. Unlike projecting onto a conventional physical screen with a single first reflection surface, the virtual projection screen medium invariably exhibits thickness and consequently any projection imaged is visible throughout the depth of the medium. As such, the image is viewed most clearly when directly in front, on-axis. This is due to the identical image alignment stacked through the depth of the screen is directly behind each other and on-axis with respect to the viewer. While the image is most clearly observed on-axis it suffers a significant viewing limitation on a low particulate (density) screen. In order to generate a highly visible image on an invisible to near-invisible screen required high intensity illumination to compensate for the low transmissivity and reflectivity of the screen cloud. This is caused by viewing directly into the bright projection source due to the high intensity illumination to compensate for a low transmissivity and reflectivity of the screen. While in a high particulate count (high density) particle cloud scenario a lower intensity illumination can compensate for the high reflectivity of the screen, this invariable causes the screen to become visibly distracting as well as require a larger and more powerful system to collect the greater amount of airborne particulates.
Additional advancements described in this invention automatically monitor changing environmental conditions such as humidity and ambient temperature to adjust cloud density, microenvironment and projection parameters in order to minimize the visibility of the particle cloud screen. This invention improves invisibility of the screen and image contrast in the multisource embodiment by projecting multiple beams at the image location to maximize illumination intensity and minimize the individual illumination source intensities.
Prior art also created a limited clear viewing zone of on or near on-axis. The projection source fan angle generates an increasingly off-axis projection towards the edges of the image, fidelity falls off where the front surface of the medium is imaging a slightly offset image throughout the depth of the medium with respect to the viewers line of sight. Since the picture is imaged thru the depth of the screen, the viewer not only sees the intended front surface image as on a conventional screen, but all the unintended illuminated particulates throughout the depth of the screen, resulting in an undefined and blurry image. In this invention, a multisource projection system provides continuous on-axis illumination visually stabilizing the image and minimizing image flutter.
This invention does not suffer from any of these aforementioned limitations, by incorporating a self-sustainability particle cloud manufacturing process, significant advances to imaging projection, advances to the microenvironment improving image fidelity, and include additional interactive capabilities.